(1) Field of the Invention
Broadly speaking, this invention relates to vapor deposition. More particularly, in a preferred embodiment, this invention relates to a nozzle beam type metal vapor source for use in the vapor deposition of electrode materials, such as gold, during the fabrication of precision quartz-crystal resonators, or the like.
(2) Discussion of the Prior Art
A critical step in the fabrication of ultra high-precision quartz-crystal resonators is the vacuum deposition of the electrode material. In order to minimize stresses that could cause aging, it is customary for both sides of the resonator to be plated simultaneously and at equal rates so that the final thicknesses of the electrodes are approximately equal. In order to minimize aging due to mass transfer, the electrode material is of high purity and is deposited rapidly under high vacuum conditions so as to minimize sorption of contaminants.
These requirements place rather stringent performance requirements on the metal vapor source used in the vacuum plating operation. Ideally it should be capable of operation over a wide range of controlled deposition rates, should be compatible with high vacuum operation, should minimize wastage of expensive electrode material, such as gold, should not require frequent maintenance, and should permit simultaneous plating of both sides of a substrate.
Unfortunately, no metal vapor source satisfying all of these performance requirements was heretofore available.